In an earlier study, Elseline Hoekzema and colleagues became the first to demonstrate that pregnancy changes the structure of the human brain. They also showed that pregnancy affects how the brain functions. For this latest research, the team followed 110 women over time. Some were expecting their first child, some were pregnant with their second, and others remained childless. By performing repeated brain scans, the researchers tracked how the brain changed throughout the study.

"With this, we have shown for the first time that the brain not only changes during the first pregnancy, but also during a second," says Hoekzema, head of the Pregnancy Brain Lab at Amsterdam UMC. "During a first and second pregnancy, the brain changes in both similar and unique ways. Each pregnancy leaves a unique mark on the female brain."

Brain Networks Shift in Different Ways

The researchers found that a first pregnancy produced the largest changes in the structure and activity of the brain's Default Mode Network, a system involved in self reflection, social thinking, and other important mental functions.

During a second pregnancy, this same network changed again, although to a lesser degree. Instead, the most noticeable changes occurred in brain networks responsible for directing attention and responding to sensory information.

"It appears that during a second pregnancy, the brain is more strongly altered in networks involved in reacting to sensory cues and in controlling your attention," explains researcher Milou Straathof, who analyzed the data. "These processes may be beneficial when caring for multiple children."

Brain Changes Linked to Maternal Bonding and Mental Health

The study also uncovered a relationship between pregnancy related brain changes and the emotional bond between mother and child. This connection was stronger after a first pregnancy than after a second.

Researchers also identified links between structural changes in the brain and peripartum depression during both first and second pregnancies. According to the team, this is the first evidence that changes occurring in the brain's cortex during pregnancy are associated with maternal depression.

The timing of these associations differed depending on pregnancy history. Among first time mothers, they were most apparent after childbirth. For women expecting a second child, they were more noticeable during pregnancy.

"This knowledge can help to better understand and recognize mental health problems in mothers. It is important that we understand how the brain adapts to motherhood."

Understanding the Maternal Brain

The findings offer new insight into the remarkable adaptability of the maternal brain. Although most women experience one or more pregnancies during their lifetime, scientists are only beginning to understand how pregnancy influences the brain over the long term.

The researchers say these discoveries help fill an important gap in knowledge about women's biology and could eventually improve care for mothers, including efforts to prevent and treat postpartum depression. The study also highlights the brain's remarkable ability to continually adapt to major life experiences such as pregnancy and motherhood.